Four port dual polarization frequency diplexer

Abstract

A diplexer for communicating signals in two different frequency bands with separate polarizations in each band may, for example, concurrently separate low frequency received signals of orthogonal polarizations from high frequency transmitted signals, also of orthogonal polarizations. To this end a common square waveguide leads to serially disposed, axially displaced, orthogonal mode transitions at which branches are made to closely coupled lowpass filters that communicate with separate ports for low frequency signal bands. A smaller square waveguide coupled to the second of the orthogonal mode transitions communicates with another orthogonal mode transition at which axially displaced branches communicate with other ports for high frequency signal bands.

What is claimed is: 
     
       1. A microwave diplexer for coupling a common port to first and second ports to transfer separately orthogonally polarized received signals in a first low frequency band, and coupling the common port to third and fourth ports to transfer separately orthogonally polarized signals to be transmitted in a second higher frequency band, comprising: means comprising a common square waveguide means having a terminus defining the common port and defining a reference axis the common square waveguide means being dimensioned to propagate both polarizations of both frequency bands;   first orthogonal mode transition means coupled to the common square waveguide means at a spaced apart region from the common port and having an arm collinear with the reference axis;   first rectangular waveguide means coupled to the first orthogonal mode transition means and including a junction therewith, the first rectangular waveguide means being oriented to transfer energy in the first frequency band of a first polarization and including low pass filter means adjacent the junction with the orthogonal mode transition means;   second orthogonal mode transition means coupled to the arm of the first orthogonal mode transition that is collinear with the reference axis and including a junction therewith, the second orthogonal mode transition means being oriented and dimensioned to transfer energy in the first frequency band of a second polarization and further propagating energy of both polarizatons in the second frequency band;   second rectangular waveguide means coupled to the second orthogonal mode transition means and including a junction therewith in a wall orthogonal to and spaced apart from the first rectangular waveguide means, the second rectangular waveguide means being oriented to transfer energy in the first frequency band of the second polarization and including low pass filter means adjacent the junction with the second orthogonal mode transition means;   second square waveguide means coupled in-line to the second orthogonal mode transition means for transfer of both orthogonally polarized signals in a second higher frequency band;   third orthogonal mode transition means coupled to the second square waveguide means, the third orthogonal mode transition means propagating energy of both polarizations in the second higher frequency band;   third rectangular waveguide means coupled to a side wall of the third orthogonal mode transition means for propagating waves of a first polarization in the second frequency band;   fourth rectangular waveguide means coupled to the third orthogonal mode transition means collinear with the reference axis for propagating waves of the second polarization in the second frequency band;   port means coupled to each of the first, second, third and fourth rectangular waveguide means; and   the first, second, and third waveguide means each include an angled corner section and a section in parallel with the reference axis, said sections being serially coupled between the associated low pass filter and the respective port means for the first and second waveguide means, and wherein each of the port means lie in a common plane normal to the reference axis.   
     
     
       2. The invention as set forth in claim 1 above, wherein the first and second rectangular waveguide means are orthogonally disposed relative to each other and displaced along the reference axis in the region of the orthogonal mode transition means. 
     
     
       3. A microwave diplexer for coupling a common port to first and second ports to transfer separately orthogonally polarized received signals in a first low frequency band, and coupling the common port to third and fourth ports to transfer separately orthogonally polarized signals to be transmitted in a second higher frequency band, comprising: means comprising a common square waveguide means having a terminus defining the common port and defining a reference axis the common square waveguide means being dimensioned to propagate both polarizations of both frequency bands;   first orthogonal mode transition means coupled to the common square waveguide means at a spaced apart region from the common port and having an arm collinear with the reference axis;   first rectangular waveguide means coupled to the first orthogonal mode transition means and including a junction therewith, the first rectangular waveguide means being oriented to transfer energy in the first frequency band of a first polarization and including low pass filter means adjacent the junction with the orthogonal mode transition means;   second orthogonal mode transition means coupled to the arm of the first orthogonal mode transition that is collinear with the reference axis and including a junction therewith, the second orthogonal mode transition means being oriented and dimensioned to transfer energy in the first frequency band of a second polarization and further propagating energy of both polarizations in the second frequency band;   second rectangular waveguide means coupled to the second orthogonal mode transition means and including a junction therewith in a wall orthogonal to and spaced apart from the first rectangular waveguide means, the second rectangular waveguide means being oriented to transfer energy in the first frequency band of the second polarization and including low pass filter means adjacent the junction with the second orthogonal mode transition means;   second square waveguide means coupled in-line to the second orthogonal mode transition means for transfer of both orthogonally polarized signals in a second higher frequency band;   third orthogonal mode transition means coupled to the second square waveguide means, the third orthogonal mode transition means propagating energy of both polarizations in the second higher frequency band;   third rectangular waveguide means coupled to a side wall of the third orthogonal mode transition means for propagating waves of a first polarization in the second frequency band;   fourth rectangular waveguide means coupled to the third orthogonal mode transition means collinear with the reference axis for propagating waves of the second polarization in the second frequency band;   port means coupled to each of the first, second, third and fourth rectangular waveguide means; and   the low pass filter means each comprise a serial arrangement of corrugated waveguide filter and reduced height ridge waveguide.   
     
     
       4. A microwave diplexer for coupling a common port to first and second ports to transfer separately orthogonally polarized received signals in a first low frequency band, and coupling the common port to third and fourth ports to transfer separately orthogonally polarized signals to be transmitted in a second higher frequency band, comprising: means comprising a common square waveguide means having a terminus defining the common port and defining a reference axis the common square waveguide means being dimensioned to propagate both polarizations of both frequency bands;   first orthogonal mode transition means coupled to the common square waveguide means at a spaced apart region from the common port and having an arm collinear with the reference axis;   first rectangular waveguide means coupled to the first orthogonal mode transition means and including a junction therewith, the first rectangular waveguide means being oriented to transfer energy in the first frequency band of a first polarization and including low pass filter means adjacent the junction with the orthogonal mode transition means;   second orthogonal mode transition means coupled to the arm of the first orthogonal mode transition that is collinear with the reference axis and including a junction therewith, the second orthogonal mode transition means being oriented and dimensioned to transfer energy in the first frequency band of a second polarization and further propagating energy of both polarizations in the second frequency band;   second rectangular waveguide means coupled to the second orthogonal mode transition means and including a junction therewith in a wall orthogonal to and spaced apart from the first rectangular waveguide means, the second rectangular waveguide means being oriented to transfer energy in the first frequency band of the second polarization and including low pass filter means adjacent the junction with the second orthogonal mode transition means;   second square waveguide means coupled in-line to the second orthogonal mode transition means for transfer of both orthogonally polarized signals in a second higher frequency band;   third orthogonal mode transition means coupled to the second square waveguide means, the third orthogonal mode transition means propagating energy of both polarizations in the second higher frequency band;   third rectangular waveguide means coupled to a side wall of the third orthogonal mode transition means for propagating waves of a first polarization in the second frequency band;   fourth rectangular waveguide means coupled to the third orthogonal mode transition means collinear with the reference axis for propagating waves of the second polarization in the second frequency band;   port means coupled to each of the first, second, third and fourth rectangular waveguide means; and   the orthogonal mode transitions are each step transitions narrowing the spacing between one opposed pair of walls of associated waveguide means.   
     
     
       5. The invention as set forth in claim 4 above, wherein the first rectangular waveguide means propagates vertically polarized signals and the first orthogonal mode transition means reduces the dimension between horizontally separated walls, wherein the second rectangular waveguide means propagates horizontally polarized signals and the second orthogonal mode transitions means reduces the dimension between vertically separated walls, wherein the third rectangular waveguide means propagates vertically polarized signals and the third orthogonal mode transition means reduces the dimension between horizontally separated walls.